Integrated Heavy Liquid Fuel Coking With Chemical Looping Concept

ABSTRACT

A process for power generation using a chemical looping combustion concept is integrated with heavy liquid fuel coking in a cracking reactor, and is configured such that petcoke deposits on metal oxide particles from the cracking reactor are used as fuel in the chemical looping combustion reaction. The process is also configured such that metal oxide particles provide the heat necessary for the cracking reaction to be initiated in the cracking reactor.

TECHNICAL FIELD

The present invention relates to a process for heavy fuel coking andchemical looping combustion to produce heat and electricity. Further,the present invention relates to the valorization of heavy fuel viain-situ production of high-value petroleum-based products and the use ofproduct gas for power generation.

BACKGROUND

Heavy oil, a variety of petroleum, is an abundant energy source that isfound throughout the world. Of the world's total oil reserves, anestimated 53 percent are in the form of heavy oil or bitumen (terms areused interchangeably). In fact, heavy oil production is estimated toincrease by 200 percent by 2030. Like the so-called “bottom of thebarrel” of conventional petroleum, heavy oil is typically carbon-richand extremely dense. Heavy oil is also highly viscous, solid ornear-solid at room temperature, and has low hydrogen content and a highmass density (e.g., API gravity of 20 degrees or less).

Despite its abundance, the refining of heavy oil has proven to be achallenge. Conventionally, multiple technologies are used to upgradevarious forms of heavy fuel, as it has been difficult to accomplish theupgrading using a single technology. For example, “vacuum distillationbottoms,” which is liquid at 300-400° C. but remains a solid at roomtemperature, represents one of the most difficult types of heavy oil ina refinery to handle and transport. However, as the value of regularcrude oil continues to increase, the need to upgrade heavy oil to asynthetic crude oil will continue to increase.

Circulating fluidized bed boilers can burn refinery by-productsefficiently and cleanly. However, these fuels tend to be difficult tohandle because they exit the refinery in liquid form at elevatedtemperatures and must be directly introduced into a combustor in thisform. Circulating fluidized bed combustion (CFB) is a conventionalindustrial process normally used for coal and petcoke combustion, andhas been the basis for the development of chemical looping combustionprocesses.

Chemical looping combustion (CLC) is a specific type of combustionprocess that was originally created in the 1950s to produce CO₂, butrecently it has received increased attention as a potential CO₂capturing process. In a conventional CLC process, an oxygen transfermaterial or “oxygen carrier” acts as an intermediate transporter ofoxygen between two different reaction zones. The first zone where thefuel is injected is called a fuel reactor, and the second zone is calledan air reactor, as air is injected into it to oxidize the oxygencarrier. Therefore, the CLC process prevents the direct contact of theair and the fuel. Typically, a solid metal oxide oxygen carrier is usedto oxidize the fuel stream in a fuel reactor. This results in theproduction of CO₂ and H₂O. The reduced form of the oxygen carrier isthen transferred to the air reactor, where it is contacted with air,re-oxidized to its initial state, and then returned back to the fuelreactor for further combustion reactions. CLC processes using a liquidhydrocarbon feed are known in the art. However, these processes do notupgrade heavy oil feeds into higher-value petroleum-based products in asingle process.

Thus, there is a need for a single technology for upgrading heavy fuelto produce valuable petroleum-based products for use in powergeneration.

SUMMARY

The present invention is directed to a process for power generationintegrating heavy liquid fuel coking with a chemical looping combustionconcept. In one or more embodiments, heavy liquid fuel in injected intoa cracking reactor along with reduced metal oxides (heat carriers),which resulting in a cracking reaction to produce petcoke deposits onthe reduced metal oxide particles. The reduced metal oxide particleswith petcoke deposits are transported from the cracking reactor to afuel reactor where they are gasified in the presence of steam to producea product gas stream, unburned gases, and reduced metal oxides. Theproduct gas stream can be used in a combined cycle unit for powergeneration. A portion of the reduced metal oxides is transported fromthe fuel reactor back to the cracking reactor, and a portion istransported from the fuel reactor to an air reactor, where the reducedmetal oxides are oxidized and then delivered back to the fuel reactor.

In one or more embodiments, one or more splitter reactors can beutilized in the system for circulating the metal oxides particles andthereby maintaining the pressure balance between the main reactors. Inone or more embodiments, high-value petroleum-based products such asnaphtha and/or gasoline can be produced from the cracking reaction inthe cracking reactor. In at least one embodiment, a riser that isfluidly connected to the fuel reactor may be utilized. In the riser, asulfur-absorbing material such as limestone is introduced and thatmaterial absorbs sulfur present in the unburned gases that weregenerated by the gasification reaction in the fuel reactor.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of the invention and its many features andadvantages will be attained by reference to the following detaileddescription and the accompanying drawing. It is important to note thatthe drawing illustrates only one embodiment of the present invention andtherefore should not be considered to limit its scope.

FIG. 1 is a schematic of a process that integrates a chemical loopingcombustion cycle with a cracking reactor.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present application relates to a chemical looping combustion processthat integrates heavy liquid fuel coking in a cracking reactor. Thechemical looping combustion process of the present applicationeliminates many of the constraints of previous chemical loopingconfigurations with liquid fuels and offers flexibility for the use ofheavy liquid hydrocarbon feeds and vacuum residue feeds. In particular,in one or more variations, the CLC process of the present applicationutilizes heavy liquid fuel that undergoes a cracking reaction in thecracking reactor resulting in petcoke deposited on metal oxideparticles. The “coked” metal oxide particles are then used as fuel forthe chemical looping combustion in the fuel reactor. Other advantagesassociated with the present application will be appreciated in view ofthe following description.

FIG. 1 illustrates an exemplary system 100 for performing the chemicallooping combustion process with integrated coking of heavy liquid fuelin accordance with the present application. FIG. 1 also shows anexemplary flow scheme that depicts a CLC process in accordance with thepresent application. In one or more embodiments, as exemplified in thesystem 100 of FIG. 1, the CLC system can have three main reaction zones:a first reaction zone defined by a cracking reactor 200; a secondreaction zone defined by a fuel reactor 300; and a third reaction zonedefined by an air reactor 400. The fuel reactor 300 can be operativelyconnected to both the cracking reactor 200 and the air reactor 400.

In one or more variations, the cracking reactor 200 is designed tofacilitate a cracking reaction involving heavy liquid fuel and metaloxide particles, and it can take any number of suitable forms. In one ormore variations, the cracking reactor 200 processes the heavy liquidfuel to produce higher value products with low boiling points, such asgasoline, gas oil, petcoke, diesel fuel, naphtha, C₁-C₄ gas, andliquefied petroleum gas (LPG). The cracking reactor 200 is designed suchthat fuel is injected into it via transport line 205. In one or morevariations, the injected fuel is a heavy liquid fuel, such as residuumfrom vacuum distillation tower (vacuum residues) which frequentlyincludes other heavy oils. In other embodiments, the fuel injected intothe cracking reactor 200 can be a solid fuel or a gas fuel.

In one or more embodiments, the heat and energy needed for the crackingreaction of the fuel in the cracking reactor 200 is delivered by themetal oxides, which act as heat carriers and as oxygen carriers. Themetal oxide particles are transported to the cracking reactor 200 viatransport line 210. In one or more embodiments, the metal oxides canform a bed in the cracking reactor 200 which is fluidized by steam. Inother variations, the cracking reactor 200 can be operated as acirculating fluidized bed or a turbulent bed. In one or moreembodiments, the metal oxides are delivered to the cracking reactor inreduced form. In one or more embodiments, the heat carrier metal oxideparticles enter the cracking reactor 200 with a temperature ranging from482° C. to 507° C. The residence time of the heat carrier metal oxideparticles in the cracking reactor 200 can range from 1 to 60 minutes,and preferentially between 10 and 30 minutes. In exemplary embodiments,the pressure in the cracking reactor 200 ranges from 15 psig to 35 psig.

Under these conditions, in at least one embodiment, cracking reactionscan proceed in the cracking reactor 200 to produce higher valueproducts. The light fractions produced by the cracking reaction are sentto a separation device 215, where they are separated into gas, gasoline,naphtha, gas oil, and/or other higher value liquid products. Thecracking reaction also results in the formation of a solid residuum ofpetcoke, which remains on the metal oxide particles (referred to hereinas “coked metal oxides”). In one or more variations, some of the liquidproducts (e.g., naphtha and gas oil) can be recycled from the separationdevice 215 back to the cracking reactor 200 via transport line 220 toincrease the petcoke yield on the metal oxide particles. In one or morevariations, steam can also be introduced into the cracking reactor 200,and in the presence of steam, the coked metal oxide particles in thefluidized bed can be gasified resulting in a product gas (e.g., CO andH₂). In other words, the coke petcoke deposits on the metal oxides canbe converted using the steam, and the rate of gasification of thepetcoke is increased in the presence of steam. In one or morevariations, baffles or packing can also be used to inhibit bypassing andthe tendency to mix vertically in the fluidized bed in the crackingreactor 200.

The petcoke generated by the cracking of the heavy liquid fuel in thecracking reactor 200 and deposited on the metal oxide particles providesa material that is then used as fuel for the chemical looping combustionin the fuel reactor 300. In other words, the metal oxides act not onlyas an oxygen carrier but also as a physical carrier for the petcokewhich then reacts when placed in the reactive conditions of the fuelreactor. The “coked” metal oxide particles are transported from thecracking reactor 200 to the fuel reactor 300 via transport line 225. Inone or more variations, the “coked” metal oxide particles can form a bedin the bottom of the fuel reactor 300, which can be fluidized by steamand/or CO₂. Steam and/or CO₂ can be injected into the fuel reactor 300via transport line 305. In the presence of steam, the “coked” metaloxides are gasified to produce a product gas stream. This product gasstream can comprise CO and H₂. In one or more embodiments, the productgas stream is syngas. In particular, the gasification reaction in thefuel reactor 300 can transform the petcoke on the metal oxide particlesinto clean syngas. In one or more embodiments, the clean syngas can thenbe utilized (e.g., burned) in a combine cycle unit that can beoperatively connected to the chemical looping unit.

The petcoke present on the metal oxide particles is gasified in the fuelreactor 300 at high temperatures, typically between 850° C. and 1200°C., and preferentially between 950° C. and 1100° C. In one or morevariations, the fuel reactor 300 is operated in a turbulent regime(turbulent bed), which promotes suitable mixing and metal oxidedistribution in the fuel reactor 300, thereby enhancing the gasificationreaction and the syngas yield. In other variations, the fuel reactor 300can be operated as a fluidized bed or a circulating fluidized bed. Theresidence time of the coked metal oxide particles in the fuel reactor300 can be between 1 and 15 minutes, and preferentially between 3 and 10minutes. However, other residence times are possible in view of thespecifics of the application and other parameters.

The fuel reactor 300 is designed based on gas superficial velocities andit can take any number of suitable forms. For exemplary fluidization gasdistribution and good metal oxide mixing, a gas superficial velocitybetween 0.3 and 1.25 m/s is desired in the bottom portion of the fuelreactor 300, and preferentially between 0.5 and 0.75 m/s.

Following the gasification reaction in the fuel reactor 300, the reducedmetal oxides, syngas, and unburned gases are then transported to theriser 310 (it will be understood that in some embodiments, the riser andfuel reactor can be combined as a single unit). In the riser 310, theunburned gases entrain portions of the relatively fine reduced metaloxide particles before passing via transport line 315 into a separatingsection 320. The syngas also passed from the riser 310 to the separatingsection 320 before exiting the system via transport line 450. In one ormore variations, a sulfur-absorbing material such as limestone can alsobe introduced into the riser 310 such that the material absorbs sulfurpresent in the gases that were generated by the gasification reaction.The product of the reaction between the sulfur and sulfur-absorbingmaterial (e.g. CaSO₄) can be eliminated from the system via theseparation section 320. In one or more variations, the separatingsection 320 can include a cyclone separator, which functions in aconventional manner to separate the entrained particulate material(reduced metal oxide particles) from the unburned gases. The separatingsection 320 can thus be thought of as being a solid/gas separator.

After separation from the unburned gases, the reduced metal oxides arerecirculated to the cracking reactor 200 and/or the fuel reactor 300. Inone or more embodiments (as shown in FIG. 1), after separation from theunburned gases in the separator section 320, the reduced metal oxideparticles are first transported via transport line 325 to a splitterreactor 330. The splitter reactor 330 maintains the pressure drop of thesystem by controlling the circulation of the metal oxide particlesbetween the fuel reactor 300 and the cracking reactor 200. After exitingthe splitting reactor, the reduced metal oxide particles can then becirculated back to the fuel reactor 300 via transport line 335 and/orback to the cracking reactor via transport line 210. In one or morevariations, the circulation rate of the metal oxide particles iscontrolled via a pressure balance unit which is a device configured tocontrol the solid circulation between the reactors. The pressure balanceunit can also provide a technical indication about the control of thesolid circulation. It will be understood that proper ducting (not shown)is provided to permit the fines of the metal oxides to pass from thefuel reactor 300 to the cracking reactor 200 via well-known separationmedia type cyclones, such as a U-beam.

Reduced metal oxides in the fuel reactor 300 can be delivered to the airreactor 400 via transport line 340 and loop seal 345 which is disposedalong transport line 340. After entering the air reactor 400, thereduced metal oxides are oxidized by air injected into the air reactor400 via transport line 405. In one or more variations, the reduced metaloxides are delivered to the bottom of the air reactor 400 where the airis injected, and thereby fluidizes the metal oxide particles. Thefluidization in the base of the air reactor 400 can ensure that thereduced metal oxide flow is stable and smooth, which allows for a moreefficient oxidation of the reduced metal oxides. The oxidation of thereduced metal oxides in the air reactor 400 is an exothermic reaction,and therefore results in the release of heat. The metal oxides are fullyoxidized in the air reactor 400 and are oxidized at a rate sufficient tolift the particles up to a separation device 410 (via transport line415) such as a cyclone, where the oxidized metal oxide particles areseparated from the flue gas. After exiting the cyclone device 410, theoxidized metal oxides can be delivered to the fuel reactor and/or theair reactor. Alternatively, in one or more embodiments, the oxidizedmetal oxides are first delivered to a splitter reactor 420 via transportline 425, as shown in FIG. 1. The splitter reactor 420 maintains thepressure between the air reactor 400 and the fuel reactor 300 viacontrol of the metal oxide circulation. Upon exiting the splitterreactor 420, the oxidized metal oxide particles can then be recirculatedto the bottom of the fuel reactor 300 via standpipe 435 and/orrecirculated back to the air reactor 400 via standpipe 445 in order tocomplete the oxidation reaction of the reduced metal oxides if it is notcomplete.

EXAMPLE

The following example is provided to better illustrate an embodiment ofthe present invention, but it should not be construed as limiting thescope of the present invention.

In this example, the metal oxide is a manganese-based metal oxide havinga density of 4190 kg/m³ and an oxygen transport capacity of about 10weight percent. Only 19.2 percent of the oxygen participates in thereaction, which results in approximately 1.92 percent of oxygentransfer. Also, in this example, heavy liquid fuel is utilized. Theamount of heavy fuel injected is approximately 10,000 barrels per day.The cracking reactor is operated to result in a cracking reactionproduct that is 10.50 percent gas, 42.11 percent liquids, and 47.31percent petcoke. In particular, the gas has the composition of C₁ tonC₄, the liquid consists of gas oil and naphtha, and the petcokecontains sulfur, which is later treated in the riser via limestoneinjection. The metal oxide required to provide the necessary amount ofoxygen to insure the partial combustion (which occurs as part of thegasification process) of the petcoke formed on the metal oxidesparticles is 1.2 tonnes/s.

The present invention provides several advancements over the prior art.First, it allows for the upgrade of heavy fuel to valuable petroleumproducts in a single process. The configuration of the present inventionalso provides an improvement over simply injecting the fuel into thefuel reactor or into a transporting zone. In particular, the injectionof the fuel directly into a fuel reactor in contact with the metal oxidecarriers can convert the fuel directly into CO₂ and H₂O for powergeneration. In contrast, the configuration of the present disclosureallows for the upgrading of heavy fuel to valuable petroleum-basedproducts, as well as for the production of petcoke to produce heat. Thusthe configuration of the present invention allows for the combining ofheavy fuel upgrading and power generation in a single process.

The present invention provides improved—and in some embodiments,complete—reduction of the oxygen carriers (metal oxides), which is notlimited by the residence time of the oxygen carriers in the fuelreactor, increasing the size of the fuel reactor to increase residencetime, or a lower oxygen carrier circulation rate. Additionally, asmentioned above, the recirculating of the reduced metal oxides to thecracking reactor provides the necessary heat for the cracking reaction.Additionally, the present invention produces petcoke in situ, therebyeliminating the needs of petcoke transportation, preparation, andheating. Further, in one or more variations, the present invention cancombine the product gas obtained from the cracking reactor, and theproduct gas from the gasification of the petcoke (e.g. syngas) in thefuel reactor to deliver the necessary gas to operate a gas turbine. Inone or more embodiments, the product gas obtained from the crackingreactor can include, but is not limited to H₂, C₁, C₂, C₃, and/or nC₄.

A further advantage of the present invention is that the circulationrate of the oxygen carrier (metal oxide) may be reduced while stillallowing for the partial reduction of the oxygen carrier in the fuelreactor. This results in faster kinetics and more energy efficientreduction of the oxygen carrier as compared with prior processes.Finally, the present invention is not limited to heavy liquid fuels, butrather allows for the flexibility of injecting other types of fuels,including solid and gas fuels.

While the present invention has been described above using specificembodiments and examples, there are many variations and modificationsthat will be apparent to those having ordinary skill in the art. Assuch, the described embodiments are to be considered in all respects asillustrative, and not restrictive. Therefore, the scope of the inventionis indicated by the appended claims, rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A method for chemical looping with integratedhydrocarbon cracking comprising the steps of: injecting at least oneliquid hydrocarbon feed into a first reactor which operates under firstreaction conditions to cause cracking of the least one liquidhydrocarbon feed in the presence of an oxygen carrier to produce a firstproduct stream and petcoke which deposits on the oxygen carrier;transferring the oxygen carrier with petcock deposited thereon from thefirst reactor to a second reactor; operating the second reactor undersecond reaction conditions to produce a second product stream and toreduce the oxygen carrier that has petcoke deposited thereon;transferring at least a first portion of the reduced oxygen carrier tothe first reactor, wherein the reduced oxygen carrier provides heat andenergy which allows the first reactor to operate under the firstreaction conditions; transferring at least a second portion of thereduced oxygen carrier to a third reactor which operates under thirdreaction conditions to oxidize the reduced oxygen carrier; andtransferring the oxidized oxygen carrier from the third reactor back tothe second reactor.
 2. The method of claim 1, wherein the first reactorcomprises a cracking reactor; the second reactor comprises a fuelreactor and the third reactor comprises an air reactor.
 3. The method ofclaim 1, wherein the at least one liquid hydrocarbon feed comprises aheavy liquid fuel.
 4. The method of claim 1, wherein the oxygen carriercomprises metal oxides.
 5. The method of claim 1, wherein the metaloxides are disposed in a bed that is within the first reactor.
 6. Themethod of claim 1, further comprising the step of injecting steam intothe second reactor to produce the second product stream which is in theform of a gas stream.
 7. The method of claim 6, wherein the gas streamcomprises syngas.
 8. The method of claim 1, wherein the second reactionconditions comprise a gasification process in which petcoke deposited onthe oxygen carrier reacts with steam and CO₂ that is injected into thesecond reactor to form syngas, whereby the oxygen carrier is reduced. 9.The method of claim 1, further comprising the step of splitting, in asplitter reactor, the reduced oxygen carrier from the second reactorinto a first portion that is returned back to the first reactor and asecond portion that is returned to the second reactor.
 10. The method ofclaim 1, further comprising the step of splitting, in a splitterreactor, the oxidized oxygen carrier from the third reactor into a firstportion that is returned back to the second reactor and a second portionthat is returned back to the third reactor.
 11. The method of claim 1,further comprising transferring the second product stream from thesecond reactor to a gas turbine for producing energy, wherein the secondproduct stream includes syngas.
 12. A process for chemical loopingcombustion with integrated hydrocarbon cracking, comprising the stepsof: injecting a heavy liquid fuel and metal oxides into a crackingreactor; cracking the heavy fuel in the cracking reactor in the presenceof the metal oxides to produce petroleum-based products and petcokedeposits on the metal oxides; delivering the metal oxides with petcokedeposited thereon from the cracking reactor to a fuel reactor; gasifyingthe metal oxides with petcoke deposited thereon in the fuel reactor inthe presence of steam to produce a product gas stream, unburned gases,and reduced metal oxides; delivering the product gas stream, unburnedgases, and the reduced metal oxides from the fuel reactor to a riser;separating the reduced metal oxides from the unburned gases and theproduct gas stream in a separation section; delivering the separatedreduced metal oxides to an air reactor; and oxidizing the reduced metaloxides in the air reactor to produce oxidized metal oxides and flue gas,wherein the oxidized metal oxides are delivered back to the fuelreactor.
 13. The process of claim 12, wherein the fuel reactor is one ofa turbulent bed, fluidized bed, and circulating fluidized bed.
 14. Theprocess of claim 12, wherein the cracking reactor is one of a turbulentbed, fluidized bed, and circulating fluidized bed.
 15. The process ofclaim 12, wherein the petroleum-based products comprise productsselected from the group consisting of naphtha, gasoline, diesel fuel,petcoke, gas oil, and LPG.
 16. The process of claim 12, furtherincluding the step of delivering the petroleum-based products from thecracking reactor to a separation device.
 17. The process of claim 16,further including the step of recycling the petroleum-based productsfrom the separation device to the cracking reactor to increase the yieldof petcoke deposited on the reduced metal oxides.
 18. The process ofclaim 12, wherein the product gas stream comprises CO and H₂.
 19. Theprocess of claim 18, wherein the product gas stream comprises syngas.20. The process of claim 19, wherein the syngas is used in a combinecycle turbine to produce electricity.
 21. The process of claim 12,wherein the unburned gases contains sulfur.
 22. The process of claim 12,further including the step of injecting a sulfur-absorbing material intothe riser.
 23. The process of claim 22, wherein the sulfur-absorbingmaterial is limestone.
 24. The process of claim 12, further includingthe steps of transporting the reduced metal oxides from the separationsection to a splitter reactor, and transporting portions of the reducedmetal oxides from the splitter reactor to the cracking reactor and thefuel reactor.
 25. The process of claim 12, further including the step oftransporting the oxidized metal oxides and flue gas from the air reactorto a separation device, wherein the oxidized metal oxides are separatedfrom the flue gas.
 26. The process of claim 25, further including thesteps transporting the oxidized metal oxides from the separation deviceto a splitter reactor, and transporting portions of the oxidized metaloxides from the splitter reactor to the fuel reactor and the airreactor.
 27. The process of claim 12, further including the step ofinjecting an air stream into the air reactor to oxidize the reducedoxygen carrier.
 28. A system that integrates heavy fuel coking andchemical looping combustion comprising: a source of heavy liquid fuel; acracking reactor in which the heavy liquid fuel and metal oxides areintroduced, and the heavy liquid fuel undergoes a cracking reaction toform petroleum-based products and petcoke particles are deposited on themetal oxides; a fuel reactor that is in fluid communication with thecracking reactor and receives the metal oxides with petcoke depositedthereon through a first conduit, the fuel reactor being configured forgasifying the metal oxides with petcoke deposits thereon with steam thatis introduced into the fuel reactor resulting in the production ofsyngas, unburned gases, and reduced metal oxides; a riser that is influid communication with the fuel reactor and receives the syngas andthe reduced metal oxides, and is in fluid communication with thecracking reactor such that a first portion of reduced metal oxides istransported from the riser to the cracking reactor and a second portionof reduced metal oxides is transported from the riser to the fuelreactor; an air reactor that is in fluid communication with the fuelreactor through a second conduit and receives reduced metal oxides fromthe fuel reactor, the air reactor including an inlet for theintroduction of air for oxidizing the reduced metal oxides to generateoxidized metal oxides and flue gases; and a third conduit that fluidlyconnects the air reactor and the fuel reactor such that a first portionof the oxidized metal oxides is transported from the air reactor to thefuel reactor, and a second portion of the oxidized metal oxides isrecycled back to the air reactor.
 29. The system of claim 28, furtherincluding a separation device in fluid communication with the crackingreactor through a fourth conduit, the separation device receiving thepetroleum-based products from the cracking reactor.
 30. The system ofclaim 28, further including a separator in fluid communication with theriser through a fourth conduit, the separator receiving the syngas andthe reduced metal oxides from the fuel reactor, separating the syngasunburned gases from the reduced metal oxides, and transporting thereduced metal oxides to the cracking reactor and the fuel reactor. 31.The system of claim 30, further including a splitter reactor formaintaining pressure balance between the cracking reactor and the fuelreactor, the splitter reactor being fluidly connected to the separatorby a fifth conduit and through which the reduced metal oxides from theseparator pass prior to being received by the cracking reactor and thefuel reactor.
 32. The system of claim 28, further including a separatorin fluid communication with the air reactor through a fourth conduit,the separator receiving the oxidized metal oxides and flue gases fromthe air reactor, separating the oxidized metal oxides from the fluegases, and transporting the oxidized metal oxides to the fuel reactorand the air reactor.
 33. The system of claim 32, further including asplitter reactor for maintaining pressure balance between the fuelreactor and the air reactor, the splitter reactor being fluidlyconnected to the separator by a fifth conduit and through which theoxidized metal oxides from the separator pass prior to being received bythe fuel reactor and the air reactor.